[7] Primary Open Angle Glaucoma Flashcards
What is glaucoma?
A group of eye conditions that lead to damage of the optic nerve and loss of retinal ganglion cells causing progressive loss of the visual fields usually due to raised intra-ocular pressure (IOP)
What can glaucoma be divided into?
- Primary vs Secondary
- Ope angle vs Closed angle
- Acute or Acute-on-chronic or Intermittent or Chronic
What is primary open angle glaucoma characterised by?
- Adult onset
- IOP at some point > 21mmHg
- Open iridocorneal angle
- Glaucomatous optic neuropathy
- Visual field loss compatible with nerve fibre damage
- Absence of underlying cause
- Usually bilateral
What is the primary problem in glaucoma?
Disease of the optic nerve
What is raised in most cases of glaucoma?
IOP
What causes raised IOP in open-angle glaucoma?
Reduced flow through the trabecular meshwork
What is the role of the trabecular meshwork?
To absorb the aqueous humour
How does the reduced flow through the trabecular meshwork in open-angle glaucoma progress?
As a chronic, painless, degenerative obstruction
What is the cause of primary open angle glaucoma?
There is no underlying cause (hence it’s called primary)😊
What are the risk factors for primary open angle glaucoma?
- Age
- Family history
- Afro-caribbean
- Ocular hypertension
- Myopia
- Retinal disease
- Diabetes
- Systemic hypertension
After what age does primary open angle glaucoma most commonly present?
65
What is myopia?
Short-sightedness
What retinal disease can increase the risk of primary open angle glaucoma?
- Central retinal vein occlusion
- Retinal detachment
- Retinitis pigmentosa
Are the majority of cases of primary open angle glaucoma symptomatic or asymptomatic?
Asymptomatic
Why are the majority of cases of primary open angle glaucoma asymptomatic ?
Because initial visual loss is in the peripheral vision which is covered by the other eye
When do patient begin to notice visual loss with primary open angle glaucoma?
When loss is severe and affects the central vision
How may primary open angle glaucoma be detected?
When checking IOP and visual fields of people with affected relatives or during a routine eye check
What abnormalities may raise suspicion of primary open angle glaucoma during a routine eye check?
- Abnormal disc
- Raised IOP
- Abnormal visual fields
How is primary open angle glaucoma clinically classified?
- Mild
- Moderate
- Severe
- End-stage
What is classified as mild primary open angle glaucoma?
Early visual field defects
What is classified as moderate primary open angle glaucoma?
Presence of arcuate scotoma (n-shaped visual field loss over central field) and thinning of the neuroretinal rim (cupping)
What is classified as severe primary open angle glaucoma?
Extensive visual field loss and marked thinning of the neuroretinal rim
What is classified as end-stage glaucoma?
Only small residual visual fields remaining with very little neuroretinal rim
What should assessment for primary open angle glaucoma involve?
- Goinoscopy
- Corneal thickness
- Tonometry
- Optic disc examination
- Visual field testing
What is goinoscopy?
Used to measure iridocorneal angle to assess whether open or closed angle glaucoma
Why should corneal thickness be assessed when investigating primary open angle glaucoma?
It can influence the IOP reading, thickened cornea can cause erroneously high reading